Abstract:

Crenarchaeotal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids and alkenones are two
types of biomarkers derived from planktonic marine micro-organisms which are used for
reconstruction of sea-surface temperatures. We determined the radiocarbon contents of the archaeal
GDGT crenarchaeol and of alkenones isolated from continental margin sediments. Systematic
differences were found between the two biomarkers, with higher radiocarbon contents in crenarchaeol
than in the phytoplankton-derived alkenones. These differences can be explained by variable
contributions of pre-aged, laterally advected material to the core sites. Crenarchaeol appears to be
more efficiently degraded during transport in oxygen-replete environments than alkenones. Whether
this reflects the influence of chemical structure or mode of protection (e.g., particle association) is not
yet known.